1. Field of the Invention
The present invention relates to a bending part which is provided at an insertion part of an endoscope.
2. Description of the Related Art
A bending part which is provided at an insertion part of an endoscope is constructed by connecting plural joint rings with rivets. Japanese Utility Model Publication No. 58-46801 discloses a structure of a bending part shown in FIG. 11, in which inner heads of rivets 1 protrude from inner peripheral faces of joint rings 2, and guide holes 3 are formed in the inner heads of the rivets 1. Each of bend-control wires 4 for controlling the bend of the bending part is inserted through the guide holes 3, and is connected with a pulley within a hand control part. The bend-control wires 4 enable bend control of the bending part by rotating control knobs provided to the axes of the pulleys.
Such conventional structure of the bending part has a problem in that the bend-control wires 4 sometimes come into contact with the joint rings 2 when the bending part operates to strongly bend. If the bend-control wire 4 is in contact with the joint ring 2, the control response becomes poor and also the bend-control wire 4 may be damaged.
The problem can be solved by guiding the bend-control wires at positions away from the inner peripheral faces of the joint rings, but in that case the rivets must protrude more from the inner peripheral faces of the joint rings. When using the structure with the more-protruding rivets, the following facts should be considered. Due to a diameter of the insertion part of an endoscope is made smaller, a diameter of the joint rings constituting the bending part has been smaller, and a filling rate (a filling density) within the bending part increases, since sizes (sectional diameters) of contents, which may be various tubes, cables, etc., in the bending part cannot be made very small. Moreover, since the rivets for connecting the joint rings also serve as guides for the bend-control wires, positions at which the rivets are arranged are limited, and the rivets cannot be arranged without interference with the contents. As a result, if the rivets greatly protrude, they block the contents and the blocking causes difficulty in arrangement of the contents and may further cause damaging of the contents. Although protection members are available for preventing such damage, addition of the protection members within the bending part further increases the filling rate.
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of a structure of a bending part of an endoscope which can prevent contact of a bend-control wire with joint rings.
In order to achieve the above-described object, the present invention is directed to a bending part of an endoscope, comprising: a plurality of joint rings, each of the plurality of joint rings having connecting parts at each of ends thereof; a plurality of rivets, each of the plurality of rivets connecting the connecting parts of adjacent two of the plurality of joint rings, each of the rivets having an inner head protruding from an inner periphery of each of the plurality of joint rings, the inner head having a wire guiding part; and a bend-control wire which is inserted in the bending part and guided with the wire guiding part of the inner head of each of the plurality of rivets, wherein at least one of the connecting parts of each of the plurality of joint rings has a cut portion for preventing contact with the bend-control wire.
According to the present invention, the bend-control wire is prevented from coming into contact with the connecting parts by providing the cut portions at the connecting parts of the joint rings; thus a control response improves and damage to the bend-control wire can be prevented.
In order to achieve the above-described object, the present invention is also directed to a bending part of an endoscope, comprising: a plurality of joint rings, each of the plurality of joint rings having connecting parts at each of ends thereof; a plurality of rivets, each of the plurality of rivets connecting the connecting parts of adjacent two of the plurality of joint rings, each of the rivets having an inner head protruding from an inner periphery of each of the plurality of joint rings, the inner head having a wire guiding part; and a bend-control wire which is inserted in the bending part and guided with the wire guiding part of the inner head of each of the plurality of rivets, wherein a distance in an insertion direction of the bend-control wire between an end of each of the connecting parts and each of the plurality of rivets connecting each of the connecting parts is shorter than a distance between the bend-control wire and each of the connecting parts.
According to the present invention, the distance in the insertion direction of the bend-control wire between the ends of the connecting parts and the rivets is shorter than the distance between the bend-control wire and the connecting parts; thus the bend-control wire can be prevented from coming into contact with the connecting parts. Therefore, the control response improves and the damage to the bend-control wire can also be prevented.